CALIBRATION CIRCUIT OF A FREQUENCY GENERATOR, frequency generator, AND COMPENSATION CIRCUIT THEREOF

ABSTRACT

A calibration circuit includes at least two compensation circuits and a comparator. The at least two compensation circuits are coupled to an input signal for outputting at least a first compensation signal and a second compensation signal respectively. The comparator is coupled to the first compensation signal and the second compensation signal for outputting a calibration signal, where the calibration signal is used for determining an oscillation frequency of a crystal oscillator to achieve a purpose of frequency compensation with a temperature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a calibration circuit and afrequency generator, and particularly to a calibration circuit that cancalibrate an oscillation frequency of a crystal oscillator according toa temperature, and a frequency generator that can stably output afrequency not influenced by the temperature.

2. Description of the Prior Art

Quartz is a naturally piezoelectric material. When an external voltageis applied to upper and lower sides of the quartz, the quartz generatesmechanical deformation due to a coupling effect between mechanical andelectrical characteristics of the quartz, resulting in a voltage dropbeing generated across the upper and lower sides of the quartz. If analternating voltage is applied to the upper and lower sides of thequartz, the quartz can generate periodic oscillations. A crystaloscillator composed of quartz has an advantage of high frequencystability, so the crystal oscillator can act as a standard frequencysource in various applications, including remote communications, mobiletelephone systems, global positioning systems, navigation, remotecontrols, aerospace industries, high-speed computers, precisionmeasurement instruments, consumer electronics, and other fields forproviding accurate frequencies.

Please refer to FIG. 1. FIG. 1 is a diagram illustrating a frequency fgenerated by the crystal oscillator varying with a temperature. As shownin FIG. 1, the frequency f generated by the crystal oscillator shiftsslightly from a target frequency f0 with the temperature, where avertical axis in FIG. 1 is a ratio of a difference Δf between thefrequency f and the target frequency f0 to the target frequency f0.Therefore, the crystal oscillator needs a calibration circuit tocompensate for a frequency error of the crystal oscillator that varieswith the temperature.

SUMMARY OF THE INVENTION

An embodiment provides a calibration circuit of a frequency generator.The calibration circuit includes at least two compensation circuits anda comparator. The at least two compensation circuits is coupled to aninput signal for outputting at least a first compensation signal and asecond compensation signal. The comparator is coupled to the firstcompensation signal and the second compensation signal for outputting acalibration signal, where the calibration signal is used for determiningan oscillation frequency of a crystal oscillator of the frequencygenerator.

Another embodiment provides a frequency generator. The frequencygenerator includes a crystal oscillator, a temperature detectioncircuit, and a calibration circuit. The crystal oscillator is used forgenerating an oscillation frequency. The temperature detection circuitis used for detecting a temperature to generate an input signal. Thecalibration circuit is coupled to the temperature detection circuit. Thecalibration circuit includes at least two compensation circuits and acomparator. The at least two compensation circuits is coupled to theinput signal for outputting at least a first compensation signal and asecond compensation signal. The comparator is coupled to the firstcompensation signal and the second compensation signal for outputting acalibration signal, where the calibration signal is used for determiningthe oscillation frequency.

Another embodiment provides a multi-order compensation unit. Themulti-order compensation unit includes a first multiplier, a secondmultiplier, and a first amplifier. The first multiplier is coupled to aninput signal and an adjustment parameter signal for outputting a firstsignal. The second multiplier is coupled to the input signal, the firstsignal, and the adjustment parameter signal for outputting a secondsignal. The first amplifier is coupled to the second signal foroutputting a compensation signal.

Another embodiment provides a multi-order compensation unit. Themulti-order compensation unit includes a first multiplier, a secondmultiplier, a first amplifier, a fourth multiplier, and a secondamplifier. The first multiplier is coupled to an input signal and aadjustment parameter signal for outputting a first signal. The secondmultiplier is coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal. The firstamplifier is coupled to the second signal for outputting a firstcompensation signal. The fourth multiplier is coupled to the inputsignal, the second signal, and the adjustment parameter signal foroutputting a third signal. The second amplifier is coupled to the thirdsignal for outputting a second compensation signal.

Another embodiment provides a multi-order compensation unit. Themulti-order compensation unit includes a first multiplier, a secondmultiplier, a first amplifier, a fourth multiplier, a second amplifier,a fifth multiplier, and a third amplifier. The first multiplier iscoupled to an input signal and a adjustment parameter signal foroutputting a first signal. The second multiplier is coupled to the inputsignal, the first signal, and the adjustment parameter signal foroutputting a second signal. The first amplifier is coupled to the secondsignal for outputting a first compensation signal. The fourth multiplieris coupled to the input signal, the second signal, and the adjustmentparameter signal for outputting a third signal. The second amplifier iscoupled to the third signal for outputting a second compensation signal.The fifth multiplier is coupled to the input signal, the third signal,and the adjustment parameter signal for outputting a fourth signal. Thethird amplifier is coupled to the fourth signal for outputting a thirdcompensation signal.

Another embodiment provides a multi-order compensation unit. Themulti-order compensation unit includes a first multiplier, a secondmultiplier, a first amplifier, a fourth multiplier, a second amplifier,a fifth multiplier, a third amplifier, a sixth multiplier, and a fourthamplifier. The first multiplier is coupled to an input signal and aadjustment parameter signal for outputting a first signal. The secondmultiplier is coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal. The firstamplifier is coupled to the second signal for outputting a firstcompensation signal. The fourth multiplier is coupled to the inputsignal, the second signal, and the adjustment parameter signal foroutputting a third signal. The second amplifier is coupled to the thirdsignal for outputting a second compensation signal. The fifth multiplieris coupled to the input signal, the third signal, and the adjustmentparameter signal for outputting a fourth signal. The third amplifier iscoupled to the fourth signal for outputting a third compensation signal.The sixth multiplier is coupled to the input signal, the fourth signal,and the adjustment parameter signal for outputting a fifth signal. Thefourth amplifier is coupled to the fifth signal for outputting a fourthcompensation signal.

The present invention provides a calibration circuit of a frequencygenerator and a frequency generator. The calibration circuit and thefrequency generator utilize at least two compensation circuits togenerate at least two compensation signals for compensating a frequencyerror of a crystal oscillator that varies with a temperature. Aplurality of compensation units included by each compensation circuit ofthe at least two compensation circuits can be combinations ofcompensation units of any order. But, the at least two compensationcircuits do not include a second-order compensation unit. In addition, athird-order compensation unit or a higher than third-order compensationunit of the at least two compensation circuits are realized by aplurality of multipliers and at least one amplifier. Because theplurality of compensation units included by each compensation circuit ofthe at least two compensation circuits can be combinations ofcompensation units of any order, the present invention can easily adjustthe at least two compensation circuits to reduce design complexity ofthe at least two compensation circuits and increase compensationaccuracy.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a frequency generated by the crystaloscillator varying with a temperature.

FIG. 2 is a diagram illustrating a calibration circuit of a frequencygenerator according to an embodiment.

FIG. 3A, FIG. 3B, and FIG. 3C are diagrams illustrating the firstcompensation unit group and the second compensation unit group accordingto different embodiments.

FIG. 3D is a diagram illustrating the second compensation signal, thethird-order compensation signal, and the first-order compensation signalin FIG. 3C versus temperature.

FIG. 4 is a diagram illustrating a first compensation unit group and asecond compensation unit group according to another embodiment.

FIG. 5 is a diagram illustrating a frequency generator according toanother embodiment.

FIG. 6 is a diagram illustrating a Gilbert-cell type multiplier.

DETAILED DESCRIPTION

Please refer to FIG. 2. FIG. 2 is a diagram illustrating a calibrationcircuit 200 of a frequency generator according to an embodiment. Thecalibration circuit 200 includes two compensation circuits 204, 206 anda comparator VR. The two compensation circuits 204, 206 are used fordescribing the present invention, and the present invention is notlimited to only the two compensation circuits 204, 206. A temperaturedetection circuit 202 is coupled to the two compensation circuits 204,206 for detecting a temperature T to generate an input signal LIV, wherea linear relationship exists between the input signal LIV and thetemperature T. The two compensation circuits 204, 206 are coupled to theinput signal LIV, and output a first compensation signal CV204 and asecond compensation signal CV206 to the comparator VR, respectively,according to the input signal LIV. The comparator VR is coupled to thefirst compensation signal CV204 and the second compensation signalCV206, and outputs a calibration signal CS according to the firstcompensation signal CV204 and the second compensation signal CV206. Thecalibration signal CS is used for determining an oscillation frequencyof a crystal oscillator VCXO, and the crystal oscillator VCXO is acrystal oscillator. The comparator VR is a varactor diode, and thecomparator VR can change the calibration signal CS according to thefirst compensation signal CV204 and the second compensation signalCV206. Therefore, the calibration circuit 200 can fine tune a frequencyerror of the crystal oscillator VCXO that varies with the temperatureaccording to the calibration signal CS that varies with the temperature.In addition, the calibration circuit 200 can include the temperaturedetection circuit 202 according to another embodiment.

As shown in FIG. 2, the compensation circuit 204 includes a firstcompensation unit group 2042 and a first adder 2044. The firstcompensation unit group 2042 includes n compensation units, and thefirst compensation unit group 2042 is coupled to the input signal LIVfor outputting a first compensation unit signal group, where n≧1. Thefirst adder 2044 is coupled to the first compensation unit signal groupfor generating the first compensation signal CV204. The compensationcircuit 206 includes a second compensation unit group 2062 and a secondadder 2070. The second compensation unit group 2062 includes mcompensation units for outputting a second compensation unit signalgroup, where m≧1. The second adder 2070 is coupled to the secondcompensation unit signal group for generating the second compensationsignal CV206. The n compensation units of the first compensation unitgroup 2042 and the m compensation units of the second compensation unitgroup 2062 can be combinations of compensation units of any order. But,the first compensation unit group 2042 and the second compensation unitgroup 2062 do not include a second-order compensation unit.

Please refer to FIG. 3A, FIG. 3B, and FIG. 3C. FIG. 3A, FIG. 3B, andFIG. 3C are diagrams illustrating the first compensation unit group 2042and the second compensation unit group 2062 according to differentembodiments. As shown in FIG. 3A, the first compensation unit group 2042includes a zeroth-order compensation unit 20420, a first-ordercompensation unit 20421, and a first adder 2044, where the zeroth-ordercompensation unit 20420 is coupled to the input signal LIV foroutputting a zeroth-order compensation signal CV0 according to the inputsignal LIV. The first-order compensation unit 20421 is coupled to theinput signal LIV for outputting a first-order compensation signal CV1according to the input signal LIV. The first adder 2044 is coupled tothe zeroth-order compensation signal CV0 and the first-ordercompensation signal CV1 for generating the first compensation signalCV204. The second compensation unit group 2062 includes a third-ordercompensation unit 2063. The third-order compensation unit 2063 includesa first multiplier 20632, a second multiplier 20634, and a firstamplifier 20636, where the third-order compensation unit 2063 is coupledto the input signal LIV for outputting a third-order compensation signalCV3 acting as the second compensation signal CV206. The first multiplier20632 has a first terminal for receiving the input signal LIV, a secondterminal for receiving the input signal LIV, a third terminal forreceiving an adjustment parameter signal T0, and an output terminal foroutputting a first signal (LIV−T0)². The second multiplier 20634 has afirst terminal for receiving the input signal LIV, a second terminal forreceiving the first signal (LIV−T0)², a third terminal for receiving theadjustment parameter signal T0, and an output terminal for outputting asecond signal (LIV−T0)³. The first amplifier 20636 has a first terminalcoupled to the second multiplier 20634 for receiving the second signal(LIV−T0)³, and an output terminal for outputting a third-ordercompensation signal CV3. In addition, a higher order compensation signal(a third-order compensation signal or a higher than third-ordercompensation signal) of the compensation circuit 204 can be generatedaccording to equation (1):

CVj=COEF(j−2)×(LIV−T0)^(j)  (1)

As shown in equation (1), a (j−2)th coefficient COEF (j−2) is providedby a (j−2)th amplifier, where j≧3, and j is a positive integer.

Therefore, the third-order compensation signal CV3 can be represented byequation (2):

CV3=COEF1×(LIV−T0)³  (2)

As shown in equation (2), a first coefficient COEF1 is provided by thefirst amplifier 20636, and the first coefficient COEF1 is a constantvalue. In addition, the first multiplier 20632 and the second multiplier20634 are Gilbert-cell type multipliers (as shown in FIG. 6). In FIG.3A, the third-order compensation signal CV3 is the second compensationsignal CV206.

As shown in FIG. 3B, the first compensation unit group 2042 includes thezeroth-order compensation unit 20420, the first-order compensation unit20421, and the first adder 2044. In addition, the first compensationunit group 2042 is described in FIG. 3A, so further descriptions thereofare omitted for simplicity. The second compensation unit group 2062includes the third-order compensation unit 2063 and a fourth-ordercompensation unit 2064, where the third-order compensation unit 2063 isdescribed in FIG. 3A, so further descriptions thereof are omitted forsimplicity. The fourth-order compensation unit 2064 includes a fourthmultiplier 20642 and a second amplifier 20644. A second adder 2070 iscoupled to the third-order compensation signal CV3 and a fourth-ordercompensation signal CV4 for generating a second compensation signalCV206. The fourth multiplier 20642 has a first terminal for receivingthe input signal LIV, a second terminal for receiving the second signal(LIV−T0)³, a third terminal for receiving the adjustment parametersignal T0, and an output terminal for outputting a third signal(LIV−T0)⁴. The second amplifier 20644 has a first terminal coupled tothe fourth multiplier 20642 for receiving the third signal (LIV−T0)⁴,and an output terminal for outputting the fourth-order compensationsignal CV4. The fourth-order compensation signal CV4 is generatedaccording to equation (1), the third signal (LIV−T0)⁴, and a secondcoefficient COEF2, where the second coefficient COEF2 is a variablecoefficient. In addition, the fourth multiplier 20642 is a Gilbert-celltype multiplier (as shown in FIG. 6). In FIG. 3B, the secondcompensation signal CV206 is generated by the second adder 2070according to equation (3), the third-order compensation signal CV3, andthe fourth-order compensation signal CV4:

CV206=CV3+CV4=COEF1×(LIV−T0)³+COEF2×(LIV−T0)⁴  (3)

As shown in FIG. 3C, the first compensation unit group 2042 includes thezeroth-order compensation unit 20420, the first-order compensation unit20421, and the first adder 2044. In addition, the first compensationunit group 2042 is described in FIG. 3A, so further description thereofis omitted for simplicity. The second compensation unit group 2062includes the third-order compensation unit 2063, the fourth-ordercompensation unit 2064, a fifth-order compensation unit 2065, and thesecond adder 2070, where the second adder 2070 is coupled to thethird-order compensation signal CV3, the fourth-order compensationsignal CV4, and a fifth-order compensation signal CV5 for generating asecond compensation signal CV206. The third-order compensation unit 2063and the fourth-order compensation unit 2064 are described in FIG. 3B, sofurther description thereof is omitted for simplicity. The fifth-ordercompensation unit 2065 includes a fifth multiplier 20652 and a thirdamplifier 20654. The fifth multiplier 20652 has a first terminal forreceiving the input signal LIV, a second terminal for receiving thethird signal (LIV−T0)⁴, a third terminal for receiving the adjustmentparameter signal T0, and an output terminal for outputting a fourthsignal (LIV−T0)⁵. The third amplifier 20654 has a first terminal coupledto the fifth multiplier 20652 for receiving the fourth signal (LIV−T0)⁵,and an output terminal for outputting the fifth-order compensationsignal CV5. The fifth-order compensation signal CV5 is generatedaccording to equation (1), the fourth signal (LIV−T0)⁵, and a thirdcoefficient COEF3, where the third coefficient COEF3 is a variablecoefficient. In addition, the fourth multiplier 20652 is a Gilbert-celltype multiplier (as shown in FIG. 6). In FIG. 3C, the secondcompensation signal CV206 is generated by the second adder 2070according to equation (4), the third-order compensation signal CV3, thefourth-order compensation signal CV4, and the fifth-order compensationsignal CV5:

$\begin{matrix}\begin{matrix}{{{CV}\; 206} = {{{CV}\; 3} + {{CV}\; 4} + {{CV}\; 5}}} \\{= {{{COEF}\; 1 \times ( {{LIV} - {T\; 0}} )^{3}} + {{COEF}\; 2 \times ( {{LIV} - {T\; 0}} )^{4}} +}} \\{{{COEF}\; 3 \times ( {{LIV} - {T\; 0}} )^{5}}}\end{matrix} & (4)\end{matrix}$

Please refer to FIG. 3D. FIG. 3D is a diagram illustrating the secondcompensation signal CV206 (CV3+CV4+CV5), the third-order compensationsignal CV3, and the first-order compensation signal CV1 in FIG. 3Cversus the temperature. As shown in FIG. 3D, the second compensationsignal CV206, the third-order compensation signal CV3, and thefirst-order compensation signal CV1 vary with the temperature.Therefore, a user can flexibly adjust a plurality of compensation unitsincluded by the two compensation circuits 204, 206 to calibrate thefrequency error of the crystal oscillator VCXO to vary exactly with thetemperature according to the frequency error of the crystal oscillatorVCXO that varies with the temperature.

In another embodiment, the first compensation unit group 2042 includesthe zeroth-order compensation unit 20420 and the first-ordercompensation unit 20421. The second compensation unit group 2062includes the third-order compensation unit 2063 to a kth-ordercompensation unit 206 k, where k≧6. In addition, subsequent operationalprinciples of the kth-order compensation unit 206 k are the same asthose of the fourth-order compensation unit 2064 and the fifth-ordercompensation unit 2065, so further description thereof is omitted forsimplicity.

Please refer to FIG. 4. FIG. 4 is a diagram illustrating a firstcompensation unit group 2042 and a second compensation unit group 2062according to another embodiment. The first compensation unit group 2042includes the zeroth-order compensation unit 20420, the first-ordercompensation unit 20421, the third-order compensation unit 20623, andthe fourth-order compensation unit 20624. The second compensation unitgroup 2042 includes the fifth-order compensation unit 2065 and asixth-order compensation unit 2066, where the sixth-order compensationunit 2066 includes a sixth multiplier 20662 and a fourth amplifier20664. Therefore, a first compensation signal CV204 in FIG. 4 isgenerated by the first adder 2044 according to equation (5), thezeroth-order compensation signal CV0, the first-order compensationsignal CV1, the third-order compensation signal CV3, and thefourth-order compensation signal CV4; and, the second compensationsignal CV206 is generated by the second adder 2070 according to equation(6), the fifth-order compensation signal CV5, and a sixth-ordercompensation signal CV6:

CV204=CV0+CV1+COEF1×(LIV−T0)³+COEF2×(LIV−T0)⁴  (5)

CV206=COEF3×(LIV−T0)⁵+COEF4×(LIV−T0)⁶  (6)

In addition, the embodiments in FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 4are only used for describing that the first compensation unit group 2042and the second compensation unit group 2062 can be combinations ofcompensation units of any order. But, the first compensation unit group2042 and the second compensation unit group 2062 do not include asecond-order compensation unit. Therefore, the present invention is notlimited to the embodiments in FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 4.

Please refer to FIG. 5. FIG. 5 is a diagram illustrating a frequencygenerator 500 according to another embodiment. The frequency generator500 includes the temperature detection circuit 202, the two compensationcircuits 204, 206, and a crystal oscillator 502. The crystal oscillator502 is used for outputting an oscillation frequency F not influenced bya temperature. Further, subsequent operational principles of the crystaloscillator 502 of the frequency generator 500 are the same as those ofthe crystal oscillator VCXO in FIG. 2, so further descriptions thereofare omitted for simplicity.

Please refer to FIG. 6. FIG. 6 is a diagram illustrating a Gilbert-celltype multiplier. As shown in FIG. 6, after an ith Gilbert-cell typemultiplier receives the adjustment parameter signal T0, the input signalLIV, and an (i−1)th signal (LIV−T0)', the ith Gilbert-cell typemultiplier outputs an ith signal (LIV−T0)^(i−1), where the (i−1)thsignal (LIV−T0)^(i) and the ith signal (LIV−T0)^(i+1) are determined byequation (7) and equation (8), respectively:

(LIV−T0)^(i)=(LIV−T0)^(i) _(—) P−(LIV−T0)^(i) _(—) N  (7)

(LIV−T0)^(i+1)=(LIV−T0)^(i+1) _(—) P−(LIV−T0)^(i+1) _(—) N  (8)

As shown in FIG. 6, equation (7), and equation (8), (LIV−T0)^(i)_P and(LIV−T0)^(i)_N are differential signals of the (i−1)th signal(LIV−T0)^(i), and (LIV−T0)^(i+1)_P and (LIV−T0)^(i+1)_N are differentialsignals of the ith signal (LIV−T0)^(i+1).

To sum up, the calibration circuit of the frequency generator and thefrequency generator utilize the at least two compensation circuits togenerate the at least two compensation signals for compensating thefrequency error of the crystal oscillator that varies with thetemperature. The plurality of compensation units included by eachcompensation circuit of the at least two compensation circuits can becombinations of compensation units of any order. But, the at least twocompensation circuits do not include the second-order compensation unit.In addition, the third-order compensation unit or the higher thanthird-order compensation unit of the at least two compensation circuitsare realized by a plurality of multipliers and at least one amplifier.Because the plurality of compensation units included by eachcompensation circuit of the at least two compensation circuits can becombinations of compensation units of any order, the present inventioncan easily adjust the at least two compensation circuits to reducedesign complexity of the at least two compensation circuits and increasecompensation accuracy.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention.

1. A calibration circuit of a frequency generator, the calibrationcircuit comprising: at least two compensation circuits coupled to aninput signal for outputting at least a first compensation signal and asecond compensation signal, respectively; and a comparator coupled tothe first compensation signal and the second compensation signal foroutputting a calibration signal, wherein the calibration signal is usedfor determining an oscillation frequency of a crystal oscillator of thefrequency generator.
 2. The calibration circuit of claim 1, wherein thecomparator is a varactor diode.
 3. The calibration circuit of claim 1,further comprising a temperature detection circuit for detecting atemperature for generating the input signal.
 4. The calibration circuitof claim 1, wherein the at least two compensation circuits comprise afirst compensation circuit and a second compensation circuit, the firstcompensation circuit comprising: a first compensation unit group coupledto the input signal for outputting a first compensation unit signalgroup; and a first adder coupled to the first compensation unit signalgroup for generating the first compensation signal; and the secondcompensation circuit comprising: a second compensation unit groupcoupled to the input signal for outputting a second compensation unitsignal group; and a second adder coupled to the second compensation unitsignal group for generating the second compensation signal.
 5. Thecalibration circuit of claim 1, wherein the at least two compensationcircuits comprise a first compensation unit group and a secondcompensation unit group, the first compensation unit group comprising: azeroth-order compensation unit coupled to the input signal foroutputting a zeroth-order compensation signal; a first-ordercompensation unit coupled to the input signal for outputting afirst-order compensation signal; and a first adder coupled to thezeroth-order compensation signal and the first-order compensation signalfor generating the first compensation signal; and the secondcompensation circuit group comprising: an Nth-order compensation unitcoupled to the input signal for outputting an Nth-order compensationsignal acting as the second compensation signal, wherein N is a positiveinteger greater than
 3. 6. The calibration circuit of claim 5, whereinthe Nth-order compensation unit comprises: a first multiplier coupled tothe input signal and an adjustment parameter signal for outputting afirst signal; a second multiplier coupled to the input signal, the firstsignal, and the adjustment parameter signal for outputting a secondsignal; and a first amplifier coupled to the second signal foroutputting the Nth-order compensation signal.
 7. The calibration circuitof claim 1, wherein the at least two compensation circuits comprise afirst compensation circuit and a second compensation circuit, the firstcompensation circuit comprising: a zeroth-order compensation unitcoupled to the input signal for outputting a zeroth-order compensationsignal; a first-order compensation unit coupled to the input signal foroutputting a first-order compensation signal; and a first adder coupledto the zeroth-order compensation signal and the first-order compensationsignal for generating the first compensation signal; and the secondcompensation circuit comprising: an Nth-order compensation unit coupledto the input signal for outputting an Nth-order compensation signalacting as the second compensation signal, wherein N is a positiveinteger greater than 3; an (N+1)th-order compensation unit coupled tothe input signal for outputting an (N+1)th-order compensation signal;and a second adder coupled to the Nth-order compensation signal and the(N+1)th-order compensation signal for generating the second compensationsignal.
 8. The calibration circuit of claim 7, wherein the Nth-ordercompensation unit comprises: a first multiplier coupled to the inputsignal and an adjustment parameter signal for outputting a first signal;a second multiplier coupled to the input signal, the first signal, andthe adjustment parameter signal for outputting a second signal; and afirst amplifier coupled to the second signal for outputting theNth-order compensation signal.
 9. The calibration circuit of claim 7,wherein the Nth-order compensation unit comprises: a first multipliercoupled to the input signal and an adjustment parameter signal foroutputting a first signal; a second multiplier coupled to the inputsignal, the first signal, and the adjustment parameter signal foroutputting a second signal; and a first amplifier coupled to the secondsignal for outputting the Nth-order compensation signal; and the(N+1)th-order compensation unit comprises: a fourth multiplier coupledto the input signal, the second signal, and the adjustment parametersignal for outputting a third signal; and a second amplifier coupled tothe third signal for outputting the (N+1)th-order compensation signal.10. The calibration circuit of claim 1, wherein the at least twocompensation circuits comprise a first compensation circuit and a secondcompensation circuit, the first compensation circuit comprising: azeroth-order compensation unit coupled to the input signal foroutputting a zeroth-order compensation signal; a first-ordercompensation unit coupled to the input signal for outputting afirst-order compensation signal; and a first adder coupled to thezeroth-order compensation signal and the first-order compensation signalfor generating the first compensation signal; and the secondcompensation circuit comprising: an Nth-order compensation unit coupledto the input signal for outputting an Nth-order compensation signalacting as the second compensation signal, wherein N is a positiveinteger greater than 3; an (N+1)th-order compensation unit coupled tothe input signal for outputting an (N+1)th-order compensation signal; an(N+2)th-order compensation unit coupled to the input signal foroutputting an (N+2)th-order compensation signal; and a second addercoupled to the Nth-order compensation signal, the (N+1)th-ordercompensation signal, and the (N+2)th-order compensation signal forgenerating the second compensation signal.
 11. The calibration circuitof claim 10, wherein the Nth-order compensation unit comprises: a firstmultiplier coupled to the input signal and an adjustment parametersignal for outputting a first signal; a second multiplier coupled to theinput signal, the first signal, and the adjustment parameter signal foroutputting a second signal; and a first amplifier coupled to the secondsignal for outputting the Nth-order compensation signal.
 12. Thecalibration circuit of claim 10, wherein the Nth-order compensation unitcomprises: a first multiplier coupled to the input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; and a firstamplifier coupled to the second signal for outputting the Nth-ordercompensation signal; and the (N+1)th-order compensation unit comprises:a fourth multiplier coupled to the input signal, the second signal, andthe adjustment parameter signal for outputting a third signal; and asecond amplifier coupled to the third signal for outputting the(N+1)th-order compensation signal.
 13. The calibration circuit of claim10, wherein the Nth-order compensation unit comprises: a firstmultiplier coupled to the input signal and an adjustment parametersignal for outputting a first signal; a second multiplier coupled to theinput signal, the first signal, and the adjustment parameter signal foroutputting a second signal; and a first amplifier coupled to the secondsignal for outputting the Nth-order compensation signal; the(N+1)th-order compensation unit comprises: a fourth multiplier coupledto the input signal, the second signal, and the adjustment parametersignal for outputting a third signal; and a second amplifier coupled tothe third signal for outputting the (N+1)th-order compensation signal;and the (N+2)th-order compensation unit comprises: a fifth multipliercoupled to the input signal, the third signal, and the adjustmentparameter signal for outputting a fourth signal; and a third amplifiercoupled to the fourth signal for outputting the (N+2)th-ordercompensation signal.
 14. The calibration circuit of claim 1, wherein theat least two compensation circuits comprise a first compensation circuitand a second compensation circuit, the first compensation circuitcomprising: a zeroth-order compensation unit coupled to the input signalfor outputting a zeroth-order compensation signal; a first-ordercompensation unit coupled to the input signal for outputting afirst-order compensation signal; an Nth-order compensation unit coupledto the input signal for outputting an Nth-order compensation signalacting as the second compensation signal, wherein N is a positiveinteger greater than 3; an (N+1)th-order compensation unit coupled tothe input signal for outputting an (N+1)th-order compensation signal;and a first adder coupled to the zeroth-order compensation signal, thefirst-order compensation signal, the Nth-order compensation signal, andthe (N+1)th-order compensation signal for generating the firstcompensation signal; and the second compensation circuit comprising: an(N+2)th-order compensation unit coupled to the input signal foroutputting an (N+2)th-order compensation signal; an (N+3)th-ordercompensation unit coupled to the input signal for outputting an(N+3)th-order compensation signal; and a second adder coupled to the(N+2)th-order compensation signal, and the (N+3)th-order compensationsignal for generating the second compensation signal.
 15. Thecalibration circuit of claim 14, wherein the Nth-order compensation unitcomprises: a first multiplier coupled to the input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; and a firstamplifier coupled to the second signal for outputting the Nth-ordercompensation signal.
 16. The calibration circuit of claim 14, whereinthe Nth-order compensation unit comprises: a first multiplier coupled tothe input signal and an adjustment parameter signal for outputting afirst signal; a second multiplier coupled to the input signal, the firstsignal, and the adjustment parameter signal for outputting a secondsignal; and a first amplifier coupled to the second signal foroutputting the Nth-order compensation signal; and the (N+1)th-ordercompensation unit comprises: a fourth multiplier coupled to the inputsignal, the second signal, and the adjustment parameter signal foroutputting a third signal; and a second amplifier coupled to the thirdsignal for outputting the (N+1)th-order compensation signal.
 17. Thecalibration circuit of claim 14, wherein the Nth-order compensation unitcomprises: a first multiplier coupled to the input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; and a firstamplifier coupled to the second signal for outputting the Nth-ordercompensation signal; the (N+1)th-order compensation unit comprises: afourth multiplier coupled to the input signal, the second signal, andthe adjustment parameter signal for outputting a third signal; and asecond amplifier coupled to the third signal for outputting the(N+1)th-order compensation signal; and the (N+2)th-order compensationunit comprises: a fifth multiplier coupled to the input signal, thethird signal, and the adjustment parameter signal for outputting afourth signal; and a third amplifier coupled to the fourth signal foroutputting the (N+2)th-order compensation signal.
 18. The calibrationcircuit of claim 14, wherein the Nth-order compensation unit comprises:a first multiplier coupled to the input signal and an adjustmentparameter signal for outputting a first signal; a second multipliercoupled to the input signal, the first signal, and the adjustmentparameter signal for outputting a second signal; and a first amplifiercoupled to the second signal for outputting the Nth-order compensationsignal; the (N+1)th-order compensation unit comprises: a fourthmultiplier coupled to the input signal, the second signal, and theadjustment parameter signal for outputting a third signal; and a secondamplifier coupled to the third signal for outputting the (N+1)th-ordercompensation signal; the (N+2)th-order compensation unit comprises: afifth multiplier coupled to the input signal, the third signal, and theadjustment parameter signal for outputting a fourth signal; and a thirdamplifier coupled to the fourth signal for outputting the (N+2)th-ordercompensation signal; and the (N+3)th-order compensation unit comprises:a sixth multiplier coupled to the input signal, the fourth signal, andthe adjustment parameter signal for outputting a fifth signal; and afourth amplifier coupled to the fifth signal for outputting the(N+3)th-order compensation signal.
 19. The calibration circuit of claim18, wherein the first multiplier, the second multiplier, the fourthmultiplier, the fifth multiplier, and the sixth multiplier areGilbert-cell type multipliers.
 20. A frequency generator, comprising: acrystal oscillator for generating an oscillation frequency; atemperature detection circuit for detecting a temperature to generate aninput signal; and a calibration circuit coupled to the temperaturedetection circuit, the calibration circuit comprising: at least twocompensation circuits coupled to the input signal for outputting atleast a first compensation signal and a second compensation signal,respectively; and a comparator coupled to the first compensation signaland the second compensation signal for outputting a calibration signal,wherein the calibration signal is used for determining the oscillationfrequency.
 21. The frequency generator of claim 20, wherein thecomparator is a varactor diode.
 22. The frequency generator of claim 20,wherein the at least two compensation circuits comprise a firstcompensation circuit and a second compensation circuit, the firstcompensation unit group comprising: a first compensation unit groupcoupled to the input signal for outputting a first compensation unitsignal group; and a first adder coupled to the first compensation unitsignal group for generating the first compensation signal; and thesecond compensation circuit comprising: a second compensation unit groupcoupled to the input signal for outputting a second compensation unitsignal group; and a second adder coupled to the second compensation unitsignal group for generating the second compensation signal.
 23. Thefrequency generator of claim 20, wherein the at least two compensationcircuits comprise a first compensation unit group and a secondcompensation unit group, the first compensation unit group comprising: azeroth-order compensation unit coupled to the input signal foroutputting a zeroth-order compensation signal; a first-ordercompensation unit coupled to the input signal for outputting afirst-order compensation signal; and a first adder coupled to thezeroth-order compensation signal and the first-order compensation signalfor generating the first compensation signal; and the secondcompensation circuit comprising: an Nth-order compensation unit coupledto the input signal for outputting an Nth-order compensation signalacting as the second compensation signal, wherein N is a positiveinteger greater than
 3. 24. The calibration circuit of claim 23, whereinthe Nth-order compensation unit comprises: a first multiplier coupled tothe input signal and an adjustment parameter signal for outputting afirst signal; a second multiplier coupled to the input signal, the firstsignal, and the adjustment parameter signal for outputting a secondsignal; and a first amplifier coupled to the second signal foroutputting the Nth-order compensation signal.
 25. The frequencygenerator of claim 20, wherein the at least two compensation circuitscomprise a first compensation circuit and a second compensation circuit,the first compensation circuit comprising: a zeroth-order compensationunit coupled to the input signal for outputting a zeroth-ordercompensation signal; a first-order compensation unit coupled to theinput signal for outputting a first-order compensation signal; and afirst adder coupled to the zeroth-order compensation signal and thefirst-order compensation signal for generating the first compensationsignal; and the second compensation circuit comprising: an Nth-ordercompensation unit coupled to the input signal for outputting anNth-order compensation signal acting as the second compensation signal,wherein N is a positive integer greater than 3; an (N+1)th-ordercompensation unit coupled to the input signal for outputting an(N+1)th-order compensation signal; and a second adder coupled to theNth-order compensation signal and the (N+1)th-order compensation signalfor generating the second compensation signal.
 26. The calibrationcircuit of claim 25, wherein the Nth-order compensation unit comprises:a first multiplier coupled to the input signal and an adjustmentparameter signal for outputting a first signal; a second multipliercoupled to the input signal, the first signal, and the adjustmentparameter signal for outputting a second signal; and a first amplifiercoupled to the second signal for outputting the Nth-order compensationsignal.
 27. The calibration circuit of claim 15, wherein the Nth-ordercompensation unit comprises: a first multiplier coupled to the inputsignal and an adjustment parameter signal for outputting a first signal;a second multiplier coupled to the input signal, the first signal, andthe adjustment parameter signal for outputting a second signal; and afirst amplifier coupled to the second signal for outputting theNth-order compensation signal; and the (N+1)th-order compensation unitcomprises: a fourth multiplier coupled to the input signal, the secondsignal, and the adjustment parameter signal for outputting a thirdsignal; and a second amplifier coupled to the third signal foroutputting the (N+1)th-order compensation signal.
 28. The frequencygenerator of claim 20, wherein the at least two compensation circuitscomprise a first compensation circuit and a second compensation circuit,the first compensation circuit comprising: a zeroth-order compensationunit coupled to the input signal for outputting a zeroth-ordercompensation signal; a first-order compensation unit coupled to theinput signal for outputting a first-order compensation signal; and afirst adder coupled to the zeroth-order compensation signal and thefirst-order compensation signal for generating the first compensationsignal; and the second compensation circuit comprising: an Nth-ordercompensation unit coupled to the input signal for outputting anNth-order compensation signal acting as the second compensation signal,wherein N is a positive integer greater than 3; an (N+1)th-ordercompensation unit coupled to the input signal for outputting an(N+1)th-order compensation signal; an (N+2)th-order compensation unitcoupled to the input signal for outputting an (N+2)th-order compensationsignal; and a second adder coupled to the Nth-order compensation signal,the (N+1)th-order compensation signal, and the (N+2)th-ordercompensation signal for generating the second compensation signal. 29.The calibration circuit of claim 28, wherein the Nth-order compensationunit comprises: a first multiplier coupled to the input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; and a firstamplifier coupled to the second signal for outputting the Nth-ordercompensation signal.
 30. The calibration circuit of claim 28, whereinthe Nth-order compensation unit comprises: a first multiplier coupled tothe input signal and an adjustment parameter signal for outputting afirst signal; a second multiplier coupled to the input signal, the firstsignal, and the adjustment parameter signal for outputting a secondsignal; and a first amplifier coupled to the second signal foroutputting the Nth-order compensation signal; and the (N+1)th-ordercompensation unit comprises: a fourth multiplier coupled to the inputsignal, the second signal, and the adjustment parameter signal foroutputting a third signal; and a second amplifier coupled to the thirdsignal for outputting the (N+1)th-order compensation signal.
 31. Thecalibration circuit of claim 28, wherein the Nth-order compensation unitcomprises: a first multiplier coupled to the input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; and a firstamplifier coupled to the second signal for outputting the Nth-ordercompensation signal; the (N+1)th-order compensation unit comprises: afourth multiplier coupled to the input signal, the second signal, andthe adjustment parameter signal for outputting a third signal; and asecond amplifier coupled to the third signal for outputting the(N+1)th-order compensation signal; and the (N+2)th-order compensationunit comprises: a fifth multiplier coupled to the input signal, thethird signal, and the adjustment parameter signal for outputting afourth signal; and a third amplifier coupled to the fourth signal foroutputting the (N+2)th-order compensation signal.
 32. The frequencygenerator of claim 20, wherein the at least two compensation circuitscomprise a first compensation circuit and a second compensation circuit,the first compensation circuit comprising: a zeroth-order compensationunit coupled to the input signal for outputting a zeroth-ordercompensation signal; a first-order compensation unit coupled to theinput signal for outputting a first-order compensation signal; anNth-order compensation unit coupled to the input signal for outputtingan Nth-order compensation signal acting as the second compensationsignal, wherein N is a positive integer greater than 3; an (N+1)th-ordercompensation unit coupled to the input signal for outputting an(N+1)th-order compensation signal; and a first adder coupled to thezeroth-order compensation signal, the first-order compensation signal,the Nth-order compensation signal, and the (N+1)th-order compensationsignal for generating the first compensation signal; and the secondcompensation circuit comprising: an (N+2)th-order compensation unitcoupled to the input signal for outputting an (N+2)th-order compensationsignal; an (N+3)th-order compensation unit coupled to the input signalfor outputting an (N+3)th-order compensation signal; and a second addercoupled to the (N+2)th-order compensation signal, and the (N+3)th-ordercompensation signal for generating the second compensation signal. 33.The calibration circuit of claim 32, wherein the Nth-order compensationunit comprises: a first multiplier coupled to the input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; and a firstamplifier coupled to the second signal for outputting the Nth-ordercompensation signal.
 34. The calibration circuit of claim 32, whereinthe Nth-order compensation unit comprises: a first multiplier coupled tothe input signal and an adjustment parameter signal for outputting afirst signal; a second multiplier coupled to the input signal, the firstsignal, and the adjustment parameter signal for outputting a secondsignal; and a first amplifier coupled to the second signal foroutputting the Nth-order compensation signal; and the (N+1)th-ordercompensation unit comprises: a fourth multiplier coupled to the inputsignal, the second signal, and the adjustment parameter signal foroutputting a third signal; and a second amplifier coupled to the thirdsignal for outputting the (N+1)th-order compensation signal.
 35. Thecalibration circuit of claim 32, wherein the Nth-order compensation unitcomprises: a first multiplier coupled to the input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; and a firstamplifier coupled to the second signal for outputting the Nth-ordercompensation signal; the (N+1)th-order compensation unit comprises: afourth multiplier coupled to the input signal, the second signal, andthe adjustment parameter signal for outputting a third signal; and asecond amplifier coupled to the third signal for outputting the(N+1)th-order compensation signal; and the (N+2)th-order compensationunit comprises: a fifth multiplier coupled to the input signal, thethird signal, and the adjustment parameter signal for outputting afourth signal; and a third amplifier coupled to the fourth signal foroutputting the (N+2)th-order compensation signal.
 36. The calibrationcircuit of claim 32, wherein the Nth-order compensation unit comprises:a first multiplier coupled to the input signal and an adjustmentparameter signal for outputting a first signal; a second multipliercoupled to the input signal, the first signal, and the adjustmentparameter signal for outputting a second signal; and a first amplifiercoupled to the second signal for outputting the Nth-order compensationsignal; the (N+1)th-order compensation unit comprises: a fourthmultiplier coupled to the input signal, the second signal, and theadjustment parameter signal for outputting a third signal; and a secondamplifier coupled to the third signal for outputting the (N+1)th-ordercompensation signal; the (N+2)th-order compensation unit comprises: afifth multiplier coupled to the input signal, the third signal, and theadjustment parameter signal for outputting a fourth signal; and a thirdamplifier coupled to the fourth signal for outputting the (N+2)th-ordercompensation signal; and the (N+3)th-order compensation unit comprises:a sixth multiplier coupled to the input signal, the fourth signal, andthe adjustment parameter signal for outputting a fifth signal; and afourth amplifier coupled to the fifth signal for outputting the(N+3)th-order compensation signal.
 37. The calibration circuit of claim36, wherein the first multiplier, the second multiplier, the fourthmultiplier, the fifth multiplier, and the sixth multiplier are Gilbertcell type multipliers.
 38. A multi-order compensation unit comprising: afirst multiplier coupled to an input signal and an adjustment parametersignal for outputting a first signal; a second multiplier coupled to theinput signal, the first signal, and the adjustment parameter signal foroutputting a second signal; and a first amplifier coupled to the secondsignal for outputting a compensation signal.
 39. A multi-ordercompensation unit comprising: a first multiplier coupled to an inputsignal and an adjustment parameter signal for outputting a first signal;a second multiplier coupled to the input signal, the first signal, andthe adjustment parameter signal for outputting a second signal; a firstamplifier coupled to the second signal for outputting a firstcompensation signal; a fourth multiplier coupled to the input signal,the second signal, and the adjustment parameter signal for outputting athird signal; and a second amplifier coupled to the third signal foroutputting a second compensation signal.
 40. A multi-order compensationunit comprising: a first multiplier coupled to an input signal and anadjustment parameter signal for outputting a first signal; a secondmultiplier coupled to the input signal, the first signal, and theadjustment parameter signal for outputting a second signal; a firstamplifier coupled to the second signal for outputting a firstcompensation signal; a fourth multiplier coupled to the input signal,the second signal, and the adjustment parameter signal for outputting athird signal; a second amplifier coupled to the third signal foroutputting a second compensation signal; a fifth multiplier coupled tothe input signal, the third signal, and the adjustment parameter signalfor outputting a fourth signal; and a third amplifier coupled to thefourth signal for outputting a third compensation signal.
 41. Amulti-order compensation unit comprising: a first multiplier coupled toan input signal and an adjustment parameter signal for outputting afirst signal; a second multiplier coupled to the input signal, the firstsignal, and the adjustment parameter signal for outputting a secondsignal; a first amplifier coupled to the second signal for outputting afirst compensation signal; a fourth multiplier coupled to the inputsignal, the second signal, and the adjustment parameter signal foroutputting a third signal; a second amplifier coupled to the thirdsignal for outputting a second compensation signal; a fifth multipliercoupled to the input signal, the third signal, and the adjustmentparameter signal for outputting a fourth signal; a third amplifiercoupled to the fourth signal for outputting a third compensation signal;a sixth multiplier coupled to the input signal, the fourth signal, andthe adjustment parameter signal for outputting a fifth signal; and afourth amplifier coupled to the fifth signal for outputting a fourthcompensation signal.